A teacher heats iron wool and then lowers it into a gas jar of halogen vapour. The demonstration is repeated with chlorine, bromine and iodine.
The table shows the teacher's observations.
| Halogen | Observation |
|---|---|
| chlorine | iron wool glows brightly; brown solid forms quickly |
| bromine | iron wool glows; brown solid forms |
| iodine | iron wool glows dimly; dark solid forms slowly |
Name the compound formed when iron reacts with chlorine.
Balance the equation for the reaction of iron with chlorine. ...... Fe+......Cl2→......FeCl3\mathrm{Fe} + ...... \mathrm{Cl_{2}} \rightarrow ...... \mathrm{FeCl_{3}}Fe+......Cl2→......FeCl3
Explain how the observations show the order of reactivity of the three halogens.
Relative atomic masses: Fe = 56, Cl = 35.5
Calculate the relative formula mass of iron chloride, FeCl3\mathrm{FeCl_{3}}FeCl3.
Calculate the percentage by mass of iron in FeCl3\mathrm{FeCl_{3}}FeCl3. Give your answer to three significant figures.
Give one reason why the demonstration is carried out in a fume cupboard.
41 exam-style questions on Edexcel GCSE Chemistry 7.2 Group 7, covering 7.2.1 Physical properties of the halogens, 7.2.2 Reactions of the halogens, 7.2.3 Relative reactivity and displacement reactions of the halogens, and 7.2.4 Halogen displacement as a redox reaction. Each one has a worked solution and a mark scheme showing where the marks go.